10 Answers
10

If your spaceship has a "propulsion-flame", change its size and color. Eg. if it normally burns with a yellow color, make it blue and double the size of it.

Apply some jitter to your spaceship. The jitter occurs due to the heavy forces caused by the boost. Maybe you could apply random roll (rotation around the spaceship forward axis).

Add some particle-effects to the wings of the spaceship.

Add some wind-like effects to the tip of the rocket/spaceship.

Update: If the look of your game allows it, you could also consider adding some speed-lines. Either at the back of your ship or as an overlay (maybe white lines) to your background-scene.

Follow-up: When writing my initial answer I was thinking about a side-scrolling game, but most of the effects can still be applied to the "follower-perspective" you chose. As mentioned by others, motion-blur is a good idea. Use a radial motion-blur, as in this example image. Instead of keeping your camera at the "normal" speed and increasing the speed of your spaceship, you could increase the camera FOV which will result in a better speed-impression. Use a trail or radial speed lines to further enhance your effect.

+1 for jitter. I am seeing the spaceship shake and shudder from the sheer power being created.
–
Tim HoltFeb 14 '11 at 20:13

Could you be more specific on the "particle-effects to the wings" ? I was thinking that on boost there should be a white skeleton-like( only on the borders of the ship) of the aircraft that looks like it and is left behind and appears for only 1-1,5 seconds and then fades .. btw i've edited my post, i added some pics.. it's a rough draft, i know
–
Badescu AlexandruFeb 15 '11 at 14:48

My 2 cents, some of it has already been said but I'd like to make my answer coherent as I believe many of these points together would create a nice effect but just alone they don't do much to create the immersion:

Random camera shaking, I used Perlin noise to make this nice. There's a C# script available over at the unifywiki.

Some blurryness spherically around the camera edges, like in the later need for speed games when travelling very fast.

Make the exhaust flame bigger and more intensive

Pull the camera back and widen the FOV, also make the colors around the edges of the camera more pale, as if the pilot is focusing really hard on what's ahead.

have some distortion effects following the ship (if the game supports render to texture shaders)

Of course, a sound to give feedback (more intensive engine sound, some kind of "moving fast through air sound" if your game allows it style wise.

Something like what happens with space ships entering the atmosphere would be cool as well, some kind of fire at the bow of the ship.

You could render the view distorted as given in actual reality by the theory of Special Relativity (you are moving fast then, right? Just remember you need to define an upper speed limit in your game then), see e.g. here.

I think relativistic distortion is a bad idea. The linked page was really fun to read however.
–
deft_codeFeb 16 '11 at 3:05

@deft_code: why not? I mean, up to ~.7c it doesn't look so extreme, and the idea "fly faster to look behind you" sound funny to me...
–
Tobias KienzlerFeb 16 '11 at 11:33

because relativity is generally unintuitive. because a similar effect can be achieved with camera frustum adjustment, and it is a well used technique in both movies and games to denote rapid movement.
–
deft_codeFeb 16 '11 at 17:15

To add on to Phil's suggestion about sound, take multiple approaches to it. You would combine multiple visual effects to achieve the sensation of speed, so do the same with sound.

Have a slight increase in volume to your thrusting sound, or crossfade to one that is more intense and "whooshy". If your collision is split into broad and narrow phase, raise an event when another object gets checked in narrow phase but doesn't actually hit. When this happens, play back a "whipping by"/Doppler effect sort of sound. You can vary it by shifting the pitch variance range upward as the difference between the velocity of the player and the velocity of the object increases.

Also kick your music up a notch, fade in a supplemental rhythm track (layered on top of your main music track). This isn't directly related to perceived speed of the player, but will help increase the emotional intensity, which is what you're after at the end of the day.

Make everything else except your ship, act like it's in slow-motion. Even if everything moves at the same speed, but just animates slower. This will give the feeling that you have an increased rate, like adrenaline or something.

They have a big problem in that everything is to scale. That make any sense of speed to be almost non-existent right up to the moment when you arrive at the star/planet/moon/.

They have the best implementation of environmental speed lines I've seen.

They denote speed by making the ship look like its flying through a thin dust cloud. As the particles stream by the leave slight speed lines. When the ship is at rest the cloud is completely transparent.